The [metal] powder in the $25, $100, $500, and $1000 is visible. (For example, that's why the green clay on the $25 looks darker than the inlay.) That distinguishes these from other chips I've had. [edit: while i can confirm metal is in the clay, i cannot confirm what kind of metal it is.]
Technically, you don't *need* any chips at all. House, clothe, and feed your family first.
If people want to make offers on specific chips, I'll be happy to post a running list of who has expressed interest in which ones. (3betChet is interested in at least the $1k chips by the way.)